The present invention is related to a two-wheel vehicle, such as a motor bicycle.
One important feature of the vehicle, or motor bicycle according to this invention resides in the fact that its motor constitutes the frame of the vehicle and thus forms an organ adapted to transmit directly the static and dynamic forces between the front part and the rear part of the vehicle. Due to the fact that the conventional frame structure is no longer used in the novel vehicle, the weight of the latter is considerably reduced and its centre of gravity is lowered to an extent unknown in the prior art.
The front suspension of a motor bicycle according to the invention has a substantially quadrilateral shape, the four corners of which are defined by the ends of two arms hingedly connected by one of their respective ends to a plate integral with the motor, while the other end of each arm is hingedly connected to a triangular piece or element supporting the axle of the front wheel.
More particularly, said two arms are both pivotally connected to said plate by means of pivots perpendicular to the plate, and to said triangular element by means of pivots adapted to permit the angular motion of said triangular element about a common axis of said pivots, the latter being furthermore mounted on ball-and-socket joints so as to be able to swing or oscillate, in response to the displacement of the suspension, about an axis pasing through the centre of each ball-and-socket joint and perpendicular to the plane of displacement which contains the said corners of the quadrilateral. The lengths and the initial position of the sides of said quadrilateral determine the shape of the curve defined, during the displacement of the front suspension, by the centre of the front wheel in a geometrical vertical plane which also encompasses the centre of the rear wheel. When suitable parameters have been chosen, it is possible to center the above-mentioned curve with respect to the rear-wheel centre. Thus the wheel-base of the vehicle, which is equal to the distance between the wheel centres, is constant. Due to this arrangement, and due to other features which will be described in detail herein-after, the vehicle is maintained in a substantially perfect horizontal position during braking, whereby the so-called "salutation reaction" is efficiently avoided.
It is furthermore possible to adjust the suspension, due to the fact that the upper one and/or the lower one of the above-mentioned arms are connected, respectively, to the pivots, by means of screws and bolts which allow the length of the arms to be varied.
The front suspension of the motor bicycle or similar vehicle is maintained in the desired position by a damping spring attached by one of its ends to the lower arm and by its other end to an upwardly extending beak formed by the plate. It will be understood that by appropriately selecting the length of the spring and the location of the point of connection or attachment of its lower end, it is possible to adjust the height of the centre of gravity within extremely wide limits. Consequently the principle of the invention can be applied to any type of vehicle, especially motor bicycles, whether they are designed for purposes of competition, sport, ordinary use, or whether they are meant to be used on tracks, on the road or on rough ground.
The steering assembly of the motor bicycle according to the invention comprises a handle-bar, a bracket having a vertical rod which is rotatably mounted in a tube supported by a tripod integrally mounted on the motor, on the upper side thereof, a substantially vertically extending control rod connected by universal joints to said bracket, on the one hand, and, on the other hand, to the end of one arm of an angle-piece the other arm of which forms a fork, a link member provided at each one of its ends with an eye, the inside of each eye being provided with a ball-and-socket-joint bushing and connected to a pivot extending through a fork located at the end of a lever integral with the triangular element. It is obvious that any one of the elements constituting this steering assembly may be provided with clearance increasing or compensating means known per se adapted to allow any appropriate adjustment to be effected.
It will also be noted that it is also possible, to simplify the steering assembly by aligning the tube, in which the above-mentioned bracket is rotatably mounted, on the axis of the control rod, whereby the uppermost universal joint becomes unnecessary and can thus be omitted. The steering is then rendered still smoother and more precise.
According to one feature of the invention, the triangular element supports a brake control device provided with a disc located in the median plane of the front wheel. Such arrangement is rendered possible by the fact that the front wheel is mounted in an cantilevered manner and that the wheel-disc can be dished on the side opposite to the suspension. This arrangement is highly advantageous in that it suppresses any dissymmetry of the reactions during braking and it renders unnecessary any reflex of the user with a view to correcting the trajectory of the vehicle while actuating the front wheel brake.
Thus the front wheel suspension is associated both to a steering assembly and the front-wheel braking means, the thus associated elements constituting a self-contained front sub-assembly wherein the forces and effects of interaction are fully withstood and balanced.
Similarly the rear part of the vehicle is also constituted by a self-contained sub-assembly capable of withstanding by itself the various forces acting on, and transmitted by, the elements of this rear sub-assembly comprising the rear-wheel proper, the rear-wheel suspension and the rear-wheel braking means, said suspension comprising a fork the arms of which are connected, on the one hand, to the hub of the wheel and, on the other hand, to a connecting piece adapted to attach the rear sub-assembly to the motor.
The rear part of the vehicle also presents the advantages brought about by the invention due to the fact that the fork which supports the rear wheel is substantially H-shaped, two arms of said fork being connected to linking pieces integral with the motor, or to bosses provided on the motor, while the other two arms of said H-shaped fork support the rear wheel hub.
In one embodiment of the invention the rear wheel suspension comprises a damping spring having an upper end connected to the top end of the connecting piece integral with the motor, and a lower end connected to one end of an arm the other end of which is hingedly connected to the bottom end of said connecting piece, said damping spring being furthermore connected to one end of a rod member, the other end of which is attached to the fork.
With a view to further reducing the so-called "salutation reaction," the lower end of the damping spring is attached through another rod member to a beak extending forwardly from the plate supporting the disc brake, said plate being mounted so as to be able to rotate about the rear wheel hub. Thus whenever the rear wheel brake is actuated, said rod member, on the one hand, limits the amplitude of the rearward displacement of the brake support and, on the other hand, acts on the lowermost attachment point of the spring so as to compress the same, whereby the suspension is "stiffened." In this respect it will also be understood that by conveniently selecting the various parameters, such as the length of the rod members and the location of the attachment points, the braking reaction effect exerted on the suspension can be varied.
Thus the motor bicycle according to the invention is novel in that it is constituted by the combination of three self-contained sub-assemblies, namely: a central sub-assembly comprising the motor and a gear-box, a front sub-assembly comprising the front wheel, guiding elements for said front wheel, the front wheel suspension braking means associated with the front wheel and steering means associated with the front wheel, and a rear sub-assembly comprising the rear wheel, the suspension associated therewith and braking means for said rear wheel, the front sub-assembly and the rear sub-assembly being connected to each other by the central sub-assembly to which they are directly attached.
In one embodiment of the invention the front sub-assembly comprises guiding elements having substantially the shape of quadrilateral the four corners of which are defined by the ends of two arms, one of their respective ends is hingedly connected to a linking plate attached to the central sub-assembly, while said two arms are connected at their other ends by ball-and-socket joints to a triangular piece which supports the axle of the front wheel.
In another embodiment the front wheel suspension is maintained in its desired position by a damping spring one end of which is attached to the lower arm of the front sub-assembly, the other end of said damping spring being attached to an upwardly extending beak formed by the linking piece or element of the sub-assembly.
In fact, the instantaneous centre of rotation of the front wheel is always located behind the axis of the rear wheel and below the horizontal plane containing the centre of gravity of the vehicle.
The self-contained nature of the sub-assemblies constituting the present motor bicycle allows, in particular, each one of said sub-assemblies to be adjusted in accordance with specific requirements, without it being necessary to take into account the other sub-assemblies while effecting such adjustments on a given sub-assembly, since each sub-assembly is capable, due to its design, of absorbing by itself the forces which are exerted on it by its various constituent elements.
The self-contained nature of the sub-assemblies obviously facilitates not only their adjustment, but also their manufacture, whereby the motor bicycle according to the invention lends itself particularly to be mass-produced.
Due to their self-contained structure, the sub-assemblies may furthermore be constructed in such a manner that they are between themselves interchangeable for example, one given type of front sub-assembly can be associated with central sub-assemblies (i.e. motors) of various HP ratings, while it is also possible to provide the latter with interchangeable rear sub-assemblies.
It will be understood that a great number of combinations can thus be achieved.
It is obvious that in the case of damage occurring to the vehicle, the repair work is greatly facilitated, as each of the sub-assemblies is directly accessible.
Furthermore, it has been shown that due to the design of the front wheel suspension, it is possible to displace rearwardly the portion of the travelling curve of the instantaneous centre of rotation, which corresponds to the displacement of the centre of the wheel with respect to the entire vehicle under the action of various loads.
The vehicle according to the invention comprises means for adjusting the length of the front wheel suspension arms, whereby the adjustment parameters can be modified easily and rapidly.
According to one feature of the invention the instantaneous centre of rotation of the front wheel is located behind the axis of the rear wheel and below the horizontal plane containing the centre of gravity of the motor bicycle.
In the present disclosure, the term "centre of gravity of the motor bicycle (or vehicle)" designates the "centre of gravity of the entirety constituted by the motor bicycle plus its driver."
The invention will be described in more detail herein-below with reference to the appended drawings which are given by way of illustration, but not of limitation.